/Engine/Source/Runtime/InteractiveToolsFramework/Public/BaseGizmos/GizmoInterfaces.h
IGizmoAxisSourceis an interface which is used to get information about a 3D Axis. At minimum this includes a 3D Direction Vector and Origin Point. Optionally the implementation may provide two Tangent Vectors which are assumed to be mutually-orthogonal and perpendicular to the Axis Direction (ie that's the normal and the 3 vectors form a coordinate frame).
class IGizmoAxisSource